Method for Controlling Injection Amount of Fuel of Burner and Aftertreating Device of Exhaust Gas

ABSTRACT

Disclosed is a method for controlling an injection amount of fuel of a burner and an aftertreating device of exhaust gas, and more particularly, to a method for controlling an injection amount of fuel of a burner and an aftertreating device of exhaust gas, in which the burner is controlled in consideration of exothermic effect due to a catalytic filter, thereby stably reducing exhaust gas.

TECHNICAL FIELD

The present invention relates to a method for controlling an injection amount of fuel of a burner and an aftertreating device of exhaust gas, and more particularly, to a method for controlling an injection amount of fuel of a burner and an aftertreating device of exhaust gas, in which the burner is controlled in consideration of exothermic effect due to a catalytic filter, thereby stably reducing exhaust gas.

BACKGROUND ART

In general, since a diesel engine has higher power and lower fuel expenses than a gasoline engine, it is widely applied to vehicles, construction equipments, ships and the like.

However, the diesel engine is a four-stroke engine in which fuel is injected into the engine and then burnt in a compression ignition method, and in a self-ignition process of the fuel, incomplete combustion occurs due to non-uniformity of a fuel-air ratio, and thus noxious particle (exhaust gas) is generated.

Particularly, the noxious particle mainly contains NO_(x), particulate matter (PM) and CO, and there is a report that the noxious particle accounts for 40% of the total air pollution. Therefore, exhaust emissions are regulated in many countries, and in order to satisfy the regulation, there has been disclosed an aftertreating device of the exhaust gas, which is inserted into a vent pipe so as to reduce the exhaust gas.

In most of the aftertreating device, the exhaust gas generated in a diesel engine is introduced into a filter having a catalyst and then burnt in the filter, thereby reducing the emissions of exhaust gas.

However, owing to low temperature of the exhaust gas when the exhaust gas is simply introduced into the filter, there has been also developed a new technique in which temperature of the exhaust gas is increased before being introduced into the filter, thereby increasing the combustion rate.

In order to increase the temperature of the exhaust gas, there have been proposed a fuel injection aftertreating device and an aftertreating device using a burner.

In the fuel injection aftertreating device, injected fuel is oxidized while being passed through a catalytic filter and/or pro catalyst, and thus temperature of the filter in which soot is collected through such reaction is increased.

However, in the fuel injection aftertreating device, since the temperature of the exhaust gas is increased using exothermic reaction occurred through the catalytic oxidation of fuel, it takes long time to obtain a target temperature value. In case that the fuel is excessively injected, non-reacted fuel is exhausted and thus environmental pollution occurs. Further, a temperature of 180° C. or more is typically needed to effectively achieve the catalytic oxidation, but if a vehicle is driven with the exhaust gas having a lower temperature than 180° C., the catalytic oxidation is not smoothly achieved. Particularly, in case that the non-reacted fuel is exhausted, milk-white smoke is discharged and may cause a serious safety problem in driving and also make an ill appearance.

In the aftertreating device using a burner, the burner is disposed between an engine and a catalytic filter so as to directly heat the exhaust gas, and the burner is operated in an engine off or idling state or an engine driving state.

In case of a method for removing the soot by operating the burner in the engine off or idling state, it is possible to stably drive the engine since the burner is operated under the same condition. However, since the burner is operated only in a state that the catalytic filter is saturated with the collected soot, it is inconvenient to intentionally stop the engine in order to operate the burner.

In case of a method for removing the soot by operating the burner in the engine driving state, it is necessary to measure a temperature of the exhaust gas introduced into the burner and a temperature at a rear end of the burner in order to decide a fuel injection amount supplied to the burner. If a pro-catalyst is provided at a front end of the catalytic filter, it is necessary to measure a temperature of the exhaust gas introduced into the pro-catalyst in order to decide a fuel injection amount supplied to the burner.

However, in case that the engine is applied to a vehicle, a temperature and an amount of the exhaust gas are rapidly changed while the vehicle is driven. Therefore, the fuel injected into the aftertreating device using the burner may be erroneously calculated comparing with an actually necessary amount.

When the fuel injection amount is decided using the temperature measured at a front end of the catalytic filter in case of using only the catalytic filter or the temperature measured at a front end of the pro-catalyst in case of using both of the pro-catalyst and the filter, it is impossible to reflect the heating effect due to heat generated while the fuel supplied to the burner is oxidized through the catalytic filter and/or pro catalyst.

In other words, if a set temperature value of the aftertreating device using the burner is 500° C., the set temperature at the rear end of the burner (the front end of the catalytic filter) is maintained within a predetermined error range. But the temperature of the exhaust gas after passing through the catalytic filter or the pro-catalyst may be 900° C. between the catalytic filter and the pro-catalyst or at the rear end of the catalytic filter, because an excessive and non-reacted hydrocarbon compound generates the heat by catalytic combustion while passing through the catalyst.

If the temperature is excessively increased as described above, durability of the filter is deteriorated, and in the worst case, the filter may be damaged.

DISCLOSURE OF INVENTION Technical Problem

An object of the present invention is to provide an aftertreating device of exhaust gas, which controls a burner in consideration of exothermic effect occurred when fuel injected from the burner passes through a catalytic filter or a pro-catalyst, thereby stably heating the exhaust gas and also efficiently reducing the emissions of exhaust gas.

Another object of the present invention is to provide an aftertreating device of exhaust gas, which properly maintains an internal temperature of the aftertreating device of exhaust gas and thus minimizes deterioration in the durability, and also which appropriately operates the burner according to a vehicle condition and a driving state.

Solution to Problem

To achieve the object of the present invention, the present invention provides a aftertreating device of exhaust gas, including a burner 30 disposed at a vent pipe 20 in which the exhaust gas generated from a diesel engine 10 is flowed and having a fuel injecting part 31 and an igniting means 32 for increasing temperature of the exhaust gas; a diesel particulate filter (DPF) 40 which is disposed at a rear side of the burner 30 in a flow direction of the exhaust gas so as to burn organic materials or particulate matters (PM) contained in the exhaust gas; a temperature sensor 70 for measuring the temperature of the exhaust gas; and a controlling part 50 which controls a fuel injection amount of the fuel injecting part 31 using an engine displacement estimated through the temperature measured from the temperature sensor 70.

Preferably, the controlling part 50 estimates the engine displacement by further using

RPM information of the diesel engine 10, and the temperature sensor 70 is disposed at a rear side of the DPF 40 in the flow direction of the exhaust gas.

Preferably, the aftertreating device 100 of exhaust gas further includes a pro-catalyst 60 disposed between the burner 30 and the DPF 40, wherein the temperature sensor 70 is disposed between the pro-catalyst 60 and the DPF 40 or at a rear side of the DPF 40 in the flow direction of the exhaust gas.

Further, the present invention provides a method for controlling an injection amount of fuel of a burner using the aftertreating device of exhaust gas as described above.

Preferably, the controlling part 50 controls the fuel injection amount so that an amount of hydrocarbon compound is 1˜3000 ppm at the rear side of the burner 30 in the flow direction of the exhaust gas.

Preferably, the controlling part 50 controls the fuel injection amount to be 0.001˜0.02 g for 1 minute per 1 l of an exhaust emission rate calculated by an equation 1 as follows:

[Equation 1]

Exhaust emission rate (E)=a·engine displacement·RPM

(a=a constant of a load factor).

Advantageous Effects of Invention

According to the method for controlling the injection amount of fuel of the burner and the aftertreating device of exhaust gas according to the present invention as described above, there is provided a sensor for controlling the fuel injection amount of the burner in consideration of the exothermic effect occurred when the fuel injected from the burner passes through the catalytic filter or the pro-catalyst, thereby efficiently reducing the emissions of exhaust gas without deterioration in the durability.

Further, the present invention appropriately operates the burner according to a vehicle condition and a driving state and prevents the problems occurred by the non-reacted fuel injected from the burner.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

FIGS. 1 and 2 are views of an aftertreating device of exhaust gas in accordance with each embodiment of the present invention.

FIG. 3 is a graph of temperature changed by controlling a fuel injection amount in the aftertreating device of exhaust gas in accordance with the present invention.

FIG. 4 is a graph showing a change in temperature in a comparative example.

DETAILED DESCRIPTION OF MAIN ELEMENTS

-   10: engine -   20: vent pipe -   30: burner -   31: fuel injecting part -   32: igniting means -   40: catalytic filter -   50: controlling part -   60: pro-catalyst -   100: aftertreating device of exhaust gas

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the embodiments of the present invention will be described in detail with reference to accompanying drawings.

FIGS. 1 and 2 are views of an aftertreating device 100 of exhaust gas in accordance with each embodiment of the present invention.

The aftertreating device 100 of exhaust gas of the present invention includes a burner 30 which is disposed at a vent pipe 20, a catalytic filter 40, a temperature sensor 70 and a controlling part 50.

The aftertreating device 100 of exhaust gas of the present invention is disposed at the vent pipe 20 through which the exhaust gas generated from a diesel engine 10 is flowed.

The burner 30 includes a fuel injecting part 31 and an igniting means 32 so as to heat the exhaust gas. The drawing shows an example that the burner 30 is disposed to be perpendicular to the vent pipe 20. The burner 30 may be disposed to be parallel with the flow of the exhaust gas or otherwise.

The catalytic filter 40 is provided at a rear side of the burner 30 in a flow direction of the exhaust gas so as to burn organic material or particulate matter (PM). The catalytic filter 40 functions to burn the exhaust gas heated by the burner 30 and thus reduce noxious material of the exhaust gas.

The controlling part 50 is a means for controlling a fuel injection amount of the fuel injecting part 31 using an engine displacement estimated through a temperature measured from a temperature sensor 70. The controlling part 50 controls the whole operation of the aftertreating device 100 of exhaust gas of the present invention.

The aftertreating device 100 of exhaust gas of the present invention is a main element for controlling the fuel injection amount of the controlling part 50, uses the temperature measured by the temperature sensor 70, and may estimate the engine displacement by further using RPM information of the diesel engine 10.

In case that the burner 30 and the catalytic filter 40 are provided, in turn, at the vent pipe 20 in the flow direction of the exhaust gas, as shown in FIG. 1, the temperature sensor 70 is provided at a rear side of the catalytic filter 40, and the controlling part 50 analyzes the temperature information measured from the temperature sensor 70, whereby the fuel injection amount of the burner 30 is controlled in consideration of the increase of the temperature due to exothermic effect of the catalytic filter.

Meanwhile, the aftertreating device 100 of exhaust gas of the present invention may further include a pro-catalyst 60 between the burner 30 and the catalytic filter 40. The pro-catalyst 60 functions to burn the organic material contained in the exhaust gas and increase the temperature of the exhaust gas. For example, a diesel oxidation catalyst (DOC) may be used as the pro-catalyst 60.

Herein, the temperature sensor 70 may be disposed between the pro-catalyst 60 and the catalytic filter 40 in the flow direction of the exhaust gas, as shown in FIG. 2, or disposed at the rear side of the catalytic filter 40 as shown in FIG. 1, or disposed between the pro-catalyst 60 and the catalytic filter 40 and also at the rear side of the catalytic filter 40.

By controlling the fuel injection amount of the burner 30 using the temperature sensor 70, the aftertreating device 100 of exhaust gas of the present invention prevents excessive increase of the temperature at a certain place and thus stably reduces the noxious material and improves the durability.

In the aftertreating device 100 of exhaust gas of the present invention, it is possible to prevent the fuel from being excessively supplied by properly controlling the fuel injection amount of the burner 30, and also to enhance the durability.

The controlling part 50 compares the temperature measured from the temperature sensor 70 and controls the fuel injection amount, whereby the fuel is properly injected so as to heat the exhaust gas to a target temperature. At this time, the fuel injection amount is controlled so that an amount of hydrocarbon compound is 1˜3000 ppm at the rear side of the burner 30 in the flow direction of the exhaust gas.

That is, the controlling part 50 compares the temperature measured through the temperature sensor 70 and decides whether to inject the fuel, thereby deciding the detailed fuel injection amount in consideration of the measured temperature and the target temperature.

Furthermore, the controlling part 50 may decide the fuel injection amount and whether to inject the fuel by additionally using the RPM information of the diesel engine 10, as a condition for deciding a vehicle state and a vehicle driving state.

Preferably, the controlling part 50 calculates an exhaust emission rate and controls the fuel injection amount to be 0.001˜0.02 g per 1 l of the exhaust emission rate for 1 minute.

The exhaust emission rate is calculated by an equation 1. The exhaust emission rate is proportional to an engine displacement and RPM of a vehicle, and a constant (a) of a load factor may be varied according to the vehicle state. And the exhaust emission rate may be calculated through repeated fuel injection operations.

[Equation 1]

Exhaust emission rate (E)=a·engine displacement·RPM

(a=a constant of a load factor)

The exhaust emission rate obtained by the engine displacement and the RPM uses as a main factor for deciding the fuel injection amount. If there is no difference between the temperature measured from the temperature sensor 70 and the target temperature, the burner 30 is not operated, and if there is a large difference therebetween, a large amount of fuel is injected within a fuel injection range calculated by the equation 1, and if there is a small difference therebetween, a small amount of fuel is injected within the fuel injection range calculated by the equation 1.

That is, in the method for controlling an injection amount of fuel in the aftertreating device of exhaust gas according to the present invention, it is possible to decide the fuel injection range in consideration of the vehicle state and also to decide the precise fuel injection amount and whether to inject the fuel, thereby efficiently reducing the noxious material of the exhaust gas.

FIG. 3 is a graph of temperature changed by controlling a fuel injection amount in the aftertreating device 100 of exhaust gas in accordance with the present invention, and FIG. 4 is a graph showing a change in temperature in a comparative example, wherein the burner 30, the pro-catalyst 60 coated with platinum and the cordierite catalytic filter 40 are provided at a truck having an engine displacement of 6800 cc, as shown in FIG. 2, and the graphs show each temperature at the front end of the pro-catalyst 60, the rear end of the pro-catalyst 60 and the rear end of the filter in a state that the target temperature is 480° C.

All of the conditions are the same as shown in FIGS. 3 and 4. In FIG. 3, the controlling parts 50 controls the fuel injection amount of the burner 30 using the temperature measured from the temperature sensor 70 disposed between the pro-catalyst 60 and the catalytic filter 40, and in FIG. 4, the controlling parts 50 controls the fuel injection amount by comparing the temperature measured from the temperature sensor 70 disposed at the front end of the pro-catalyst 60.

As shown in FIG. 3, in the method for controlling an injection amount of fuel of the burner and the aftertreating device of exhaust gas according to the present invention, a maximum temperature is 530° C. or less, and the temperature distribution is relatively uniform, comparing with FIG. 4.

However, in the comparative example of FIG. 4, since the maximum temperature is increased to 720° C. , it is apprehended that the durability is deteriorated.

The present application contains subject matter related to Korean Patent Application No. 10-2009-0069951, filed in the Korean Intellectual Property Office on Jul. 30, 2009, the entire contents of which is incorporated herein by reference.

While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

INDUSTRIAL APPLICABILITY

In the method for controlling an injection amount of fuel of the burner and the aftertreating device of exhaust gas according to the present invention, as described above, since the fuel injection amount of the burner is controlled in consideration of the increase in the temperature of the exhaust gas due to the pro-catalyst 60 or the catalytic filter 40, it is possible to stably operate the device, thereby efficiently reducing the noxious material of the exhaust gas. 

1. An aftertreating device of exhaust gas, comprising: a burner disposed at a vent pipe in which the exhaust gas generated from a diesel engine is flowed and having a fuel injecting part and an igniting means for increasing temperature of the exhaust gas; a diesel particulate filter (DPF) which is disposed at a rear side of the burner in a flow direction of the exhaust gas so as to burn organic materials or particulate matters (PM) contained in the exhaust gas; a temperature sensor for measuring the temperature of the exhaust gas; and a controlling part which controls a fuel injection amount of the fuel injecting part using an engine displacement estimated through the temperature measured from the temperature sensor.
 2. The aftertreating device of claim 1, wherein the controlling part estimates the engine displacement by further using RPM information of the diesel engine.
 3. The aftertreating device of claim 1, wherein the temperature sensor is disposed at a rear side of the DPF in the flow direction of the exhaust gas.
 4. The aftertreating device of claim 1, further comprising a pro-catalyst disposed between the burner and the DPF, wherein the temperature sensor is disposed between the pro-catalyst and the DPF or at a rear side of the DPF in the flow direction of the exhaust gas.
 5. A method for controlling an injection amount of fuel of a burner in the aftertreating device of claim
 1. 6. The method of claim 5, wherein the controlling part controls the fuel injection amount so that an amount of hydrocarbon compound is 1˜3000 ppm at the rear side of the burner in the flow direction of the exhaust gas.
 7. The method of claim 6, wherein the controlling part controls the fuel injection amount to be 0.001˜0.02 g for 1 minute per 1 l of an exhaust emission rate calculated by an equation 1 as follows: [Equation 1] Exhaust emission rate (E)=a·engine displacement·RPM (a=a constant of a load factor).
 8. A method for controlling an injection amount of fuel of a burner in the aftertreating device of claim
 2. 9. A method for controlling an injection amount of fuel of a burner in the aftertreating device of claim
 3. 10. A method for controlling an injection amount of fuel of a burner in the aftertreating device of claim
 4. 11. The method of claim 8, wherein the controlling part controls the fuel injection amount so that an amount of hydrocarbon compound is 1˜3000 ppm at the rear side of the burner in the flow direction of the exhaust gas.
 12. The method of claim 9, wherein the controlling part controls the fuel injection amount so that an amount of hydrocarbon compound is 1˜3000 ppm at the rear side of the burner in the flow direction of the exhaust gas.
 13. The method of claim 10, wherein the controlling part controls the fuel injection amount so that an amount of hydrocarbon compound is 1˜3000 ppm at the rear side of the burner in the flow direction of the exhaust gas.
 14. The method of claim 11, wherein the controlling part controls the fuel injection amount to be 0.001˜0.02 g for 1 minute per 1 l of an exhaust emission rate calculated by an equation 1 as follows: [Equation 1] Exhaust emission rate (E)=a·engine displacement·RPM (a=a constant of a load factor).
 15. The method of claim 12, wherein the controlling part controls the fuel injection amount to be 0.001˜0.02 g for 1 minute per 1 l of an exhaust emission rate calculated by an equation 1 as follows: [Equation 1] Exhaust emission rate (E)=a·engine displacement·RPM (a=a constant of a load factor).
 16. The method of claim 13, wherein the controlling part controls the fuel injection amount to be 0.001˜0.02 g for 1 minute per 1 l of an exhaust emission rate calculated by an equation 1 as follows: [Equation 1] Exhaust emission rate (E)=a·engine displacement·RPM (a=a constant of a load factor). 